This invention relates to methods of winding electric motor armatures, and more particularly to methods of winding armatures with a modified side pattern.
Various schemes for winding electric motor armatures are known as shown, for example, in Mommsen et al. U.S. Pat. No. 3,448,311, Miller U.S. Pat. No. 3,913,220, and Dammar U.S. Pat. No. 3,927,843. Despite the existence of alternative winding schemes such as are shown in these references, the so-called "side" pattern remains popular for certain applications such as low voltage, high current electric motors used in automobiles.
FIG. 1 shows side pattern coils wound on an armature 50 by one flyer 84 or 87 in a dual flyer winding machine 80 (see FIG. 3). FIG. 2 shows the similar coils simultaneously wound on the same armature by the other flyer of the winder. (In all of the drawings like FIGS. 1 and 2 the coils are simplified for greater clarity by omitting the leg of each coil which is closest to commutator 54.) Considering FIG. 1 initially, coil winding by the first flyer begins by passing the wire from that flyer through the tang on commutator member 1. Then the wire is alternately passed through armature slots A and F until the desired number of turns has been produced in coil b1. Thereafter, from slot F, the wire is drawn back to the tang on commutator member 2. From commutator tang 2 the wire is wound around slots B and G to produce coil b2, and then the wire is drawn back to commutator tang 3. This process continues until all of coils b1 through b6 have been wound one after another. Winding by the first flyer is concluded by passing the wire out through commutator tang 7.
At the same time that coil b1 is being wound, a similar coil b7 is being wound by the other flyer on the diametrically opposite side of the armature as shown in FIG. 2. The wire for coil b7 starts at commutator tang 7 and is wound through slots G and N. After coil b7 has been wound, the wire returns to commutator tang 8, from which the wire is subsequently drawn around slots H and A to produce coil b8 concurrently with the winding of coil b2. Again this process continues until all of coils b7 through b12 have been wound, and winding by the second flyer is concluded by passing the finish lead from coil b12 out through commutator tang I.
In the conventional dual flyer winder 80 shown in FIG. 3 (see also the above mentioned Miller and Dammar patents) the relative motion between the wires and armature 50 required to wind the armature is produced by rotating the wire dispensing flyers about an axis 75 which is perpendicular to the longitudinal axis of the armature, and by rotating the armature about its longitudinal axis. To produce the pure side pattern shown in FIGS. 1 and 2 it is typically only necessary to rotate the armature one slot increment after each diametrically opposite pair of coils has been wound.
It will be noted that in the side pattern the start and finish leads of each coil run substantially directly to an armature tang which is on the same side of the armature as the coil and which is angularly between the slots on which the coil is wound. Because of this substantially direct routing, the start and finish leads are typically not in contact-with the central armature shaft 56 which runs between the core and commutator regions 52 and 54 of the armature (see FIG. 4). One consequence of this is that, as winding proceeds, the later coils deposited by each flyer tend to bear on the leads of the coils deposited earlier by the other flyer. As shown in FIGS. I and 2, for example, coils b10, b11, and b12 wound by the second flyer bear on leads L1, L2, and L3 formed by the first flyer. Similarly, coils b4, b5, and b6 wound by the first flyer bear on leads LR1, LR2, and LR3 formed by the second flyer. The coils which thus bear on the leads of other coils tend to be forced radially farther out than previously wound coils. This causes nonuniform distribution of mass around the armature, which can make the armature more difficult to balance.
Another disadvantage of the above-described winding pattern is that for armatures requiring a high slot fill with tight wire winding, the later-deposited coils can overstress and break the unsupported lead wires of the previously deposited coils on which the later coils bear.
Despite the foregoing drawbacks of the side pattern, that pattern continues to be favored for certain motors because it has several benefits as compared to the known alternatives such as those shown in the above-mentioned Miller patent. Among these benefits are shorter start and finish leads, less need for axial space between the core and commutator portions 52 and 54 of the armature (thereby allowing the armature to be made shorter), and more efficient air circulation for cooling the coil ends which are located between the core and commutator portions of the armature because of the space left open under the start and finish leads. This last advantage is especially important for low voltage, high current motors such as are used in automobiles, and of course applies only if the coils are not impregnated.
In view of the foregoing it is an object of this invention to provide methods for winding armatures with a modified side pattern which has at least some of the advantages of the conventional side pattern, while ameliorating the disadvantages of that conventional pattern.